For the purpose of simplifying a process for preparing TN-type liquid crystal display elements and reducing its cost, there has previously used an organic polymer film as a support layer for a polarizing film and to provided its surface with a transparent electrically conductive film so that the polarizing film and the transparent electrically conductive film may be integrated. As a support layer for a polarizing film, there has hitherto been used an acetate film, for example, a triacetate cellulose film (TAC film). However, in the production of an integral type, the TAC film has the defects that it cannot resist the conditions in sputtering or vacuum deposition for forming a transparent electrically conductive film of high quality and the conditions in assembling liquid crystal display elements because it is inferior in heat resistance. It is not desirable either from the aspect as a support layer for a polarizing film that the film has low heat resistance.
Films including polyester, which have hitherto been studied as transparent electrically conductive films, are subjected to orientation by stretching in order to exhibit their high molecular characteristics and thus have optical anisotropy. The optical anisotropy is a fatal defect for TN-type liquid crystal display elements which employ the polarization of light.
As a polarizing element which is incorporated in a polarizing film, iodine has hitherto been used and organic dyes have recently been investigated also organic dyes. However, iodine has a large sublimability and thus is insufficient in its heat resistance when it is incorporated in a polarizing film as a polarizing element. As regards the organic dyes, the conventional ones were considerably inferior to iodine in polarizing property.
For the purpose of achieving the simplification and cost reduction in the production process of a TN-type liquid crystal display element by making an integral type of a polarizing film and a transparent electrically conductive film which have been difficult to achieve, there has been a requirement for the development of a polarizing element having a satisfactory heat resistance and a polarizing property comparable to that of iodine, the development of a resin capable of forming the integral structure with a polarizing film containing the polarizing element therein, and the like.